Laser Heating Substrate Etching Uniformity
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Solution Overview
Problem
Current etching processes for semiconductor substrates, particularly in vertical NAND flash memory production, face challenges in achieving high selectivity and uniformity in etching silicon nitride films while minimizing silicon oxide film etching and temperature fluctuations.
Innovation Solution
A substrate treatment apparatus and method that utilizes a laser irradiation unit to repeatedly heat and cool the substrate, maintaining a preset temperature by adjusting the duty ratio and intensity of laser pulses, creating a temperature gradient in the etching solution to enhance etching selectivity and uniformity, and includes a chemical supply unit and recovery system for efficient etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a batch-type etching apparatus is used to etch silicon nitride films, then the etching process can be performed, but it is difficult to obtain good uniformity in etching rate and good etching selectivity
Solution Approach 1:
The patent applies periodic heating and cooling cycles to the substrate during the etching process. The substrate is repeatedly heated to a predetermined temperature and then cooled, creating periodic thermal cycles that enhance etching uniformity and selectivity. This periodic thermal action prevents the formation of temperature gradients that would cause non-uniform etching, while maintaining the chemical etching process effectiveness.
2Temperature
If the substrate is continuously heated to maintain temperature, then etching can proceed, but temperature fluctuations occur during the etching process
Solution Approach 1:
The patent implements periodic heating and cooling cycles rather than continuous heating. The substrate temperature is repeatedly raised to a predetermined temperature and then allowed to cool, creating controlled thermal cycles. This periodic action prevents temperature accumulation and fluctuations, maintaining stable average temperature while improving etching uniformity through the cyclic thermal stress applied to the substrate.
Solution Approach 2:
The patent employs a temperature measurement member to monitor substrate temperature in real-time and feeds this information back to the heating control system. Based on the measured temperature, the controller adjusts the heating power dynamically, reducing heating when temperature rises and increasing heating when temperature drops. This feedback control mechanism maintains stable substrate temperature throughout the etching process, preventing temperature fluctuations that would compromise etching uniformity.
3Productivity
If high etching rate is achieved, then productivity increases, but etching selectivity between silicon nitride and silicon oxide films decreases
Solution Approach 1:
The patent utilizes periodic heating and cooling cycles to enhance etching selectivity while maintaining productivity. During the heating phases, the etching reaction rate increases for both silicon nitride and silicon oxide films. However, the cyclic thermal stress selectively accelerates silicon nitride etching while suppressing silicon oxide etching, achieving higher selectivity. The periodic nature of the process allows sufficient etching rate to be maintained over the complete cycle while improving the selectivity ratio between the two materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high etching selectivity and improved uniformity in vertical etching, minimizing temperature fluctuations and optimizing the etching rate by creating a vortex in the etching solution through controlled temperature management.
Implementation Method 1
a laser irradiation unit configured to apply a laser pulse to the substrate to heat the substrate
Implementation Method 2
creating a temperature gradient in the etching solution to enhance etching selectivity and uniformity
Implementation Method 3
improving etching uniformity in a vertical direction in which films are stacked by causing a vortex in an etching solution
Implementation Method 4
the substrate is repeatedly heated and cooled to maintain a preset temperature
Data Source
AI summary
A substrate treatment apparatus includes a substrate support unit, a chemical supply unit supplying a chemical solution onto an upper surface of a substrate supported on the substrate support unit, a laser irradiation unit applying a laser pulse to the substrate to heat the substrate, and a controller controlling the laser irradiation unit to emit the laser pulse such that the substrate is repeatedly heated and cooled to maintain a preset temperature.